1. Field of the Invention
The present invention relates to a machine tool having a column that is movable in at least one direction on a carriage, and more particularly to a machine tool having a cover member for covering an open portion on an upper surface of a carriage.
2. Description of Related Art
FIG. 11 depicts a related machine tool 101 having a main shaft head 106 that supports a tool 107 for processing a workpiece (not shown). A column 105 supports the main shaft head 106. The column 105 is located on a carriage 104 and is freely slidable along an axis in a forward and backward direction. The carriage 104 is freely slidable along another axis in right and left directions. The carriage 104 contains an open upper portion. The carriage 104 further includes a driving mechanism for moving the column 105. The driving mechanism includes a Z-axis feeding screw 117, a Z-axis feeding screw nut 116 and, a Z-axis guide 115, which are positioned in open the upper portion of the carriage 104.
The machine tool 101 includes cover member 131 that covers the upper opened portion of the carriage 104, as shown in FIG. 11. The cover member 131 prevents chips produced during processing of a workpiece and cutting oil from entering the driving mechanism. The cover member 131 follows the forward and backward movement of the column 105. One end 131A of the cover member 131 is secured to a front lower end portion 105A of the column 105, as shown in FIG. 11. The cover member 131 extends over the upper side of the carriage 104 and down the front side of the carriage 104. The cover member 131 is bent in U-shape and then fixed to the carriage 104, as shown in FIGS. 11 and 12.
As described above, the cover member 131 hangs down at the front side of the carriage 104 and is fixed to the carriage 104, as shown in FIG. 12. This arrangement of the cover member 131, however, causes chips 144 to be trapped inside the cover member 131, as shown in FIG. 12. The trapped chips 144 prevent a smooth movement of the column 105.